Road-paving machine



Oct. 15, 1968 B. L.. GUSTAFSON ROAD-PAVING MACHINE Filed April INVENTOR.

BEAUFORD L. GUSTAFSON BY @W V ATTORNEYS 3,405,613 ROAD-PAVING MACHINE Beauford L. Gustafso'n, 1700 E. Campbell,

Phoenix, Ariz. 85016 Filed Apr. 20, 1967, Ser.- No. 632,360

' 3 Claims. (Cl. 94-44) V ABSTRACT OF THE DISCLOSURE Background of the invention This invention relates to road maintenance equipment.

More particularly, the invention concerns an improved road paving or re-surfacing machine.

In a further aspect, the invention relates to an improved paving machine for dispensing and spreading paving aggregate furring the construction or re-surfacing of roadways.

In a still further aspect, the invention concerns an improved paving machine of the above type adapted to separate oversized material, including trash, agglomerates, and foreign material from the aggregate and further adapted to expel the rejected material at a location remote from the surface to be paved.

During road maintenance'work involving new paving or re-surfacing it is conventional practice to accumulate and store the paving aggregate in deposits along the construction site or at a remote location in advance of the paving operation. After the road bed has been properly prepared a road paving machine is employed to dispense and spread the paving aggregate. The most commonly used road paving machine is a self-propelled device having a receiving hopper to receive paving aggregate from a dump-truck, a discharge hopper-to dispense and spread theaggregate upon the surface to be paved, and an aggregate conveyor communicating between the receiving hopper and the discharge hopper. Depending on the character of the construction and the mode of storage, either a truck or a loader is used to transport the paving aggregate from storage to the receiving hopper of the paving machine.

Frequently the paving aggregate, usually sized gravel, crushed rock, or bituminous mixture, is stored for an extended period of time or under adverse conditions, during which substantial quantities of undesirable material, including trash, agglomerates, and foreign objects, may contaminate the paving aggregate. Other undesirable elements may be scooped up from the ground by the loader when lifting the aggregate storage deposit.

While dust and diminutive foreign material are tolerable, foreign material substantially larger than the aggregate is detrimental to the paving process. It is necessary then that oversized materials be separated. This is usually accomplished manually at the expense of additional labor and intermittent work stoppages.

It would be highly advantageous, therefore, to provide convenient means to separate undesirable material from the paving aggregate after the stored aggregate is dumped into the paving machine.

Summary of the invention Accordingly, his a principal objectof the present invention to,- provide-an improved road paving machine which efficiently separates oversized material including trash, agglomerates, and foreign material from the pav ing aggregate. p 1

Another object of the present invention is to provide an improved road paving machine which expels therejected material at a point remote from the surface to be paved. p

In accordance with a preferred embodiment .of my invention I provide an inclined screen or grate (commonly referred to in the art as a grizzly) extending from the discharge end of the aggregate conveyor downwardly over the mouth of the discharge hopper. The screen is suspended at the lower forward edge bya flexible coupling preferably a short section of chain, while the upper rear end is united with an eccentric drive for imparting a vibrating motion. The vibrating inclined screen has a tendency to break up agglomerates of paving aggregate, allowing the passage of sized material. Oversized material is carried downwardly to the lower edge of the discharge hopper. An expulsion conveyor is positioned below the lower edge of the inclined screen and receives the oversized material and trash from the screen and empties it into a chute which ultimately expels the rejected material at a point remote from the surface to be paved.

Description of the drawings A more comprehensive understanding of the invention and further and more specific objects and advantages thereof, will become apparent to those skilled in the art from the following detailed description of the invention taken in conjunction with the drawings in which:

FIG. 1 is a perspective view of an improved paving machine embodying the present invention, which is chosen for purposes of illustration.

FIG. 2 is a partial perspective view showing the discharge end of the expulsion conveyor.

FIG. 3 is an elevation view, partly schematic, particularly detailing the operative relationship of the trash removal elements of the present invention, and

FIG. 4, partly in section taken along the line 4-4 of FIG. 3, further illustrates the elements of FIG. 3.

Description of the preferred embofdiment Turning now to the drawings in which the same reference numerals indicate corresponding elements throughout the several views, FIG. 1 illustrates a conventional self-propelled road paving machine generally designated by the reference charafter 10. A receiving hopper 11, extending along the rear of the machine, accepts the paving aggregate from the transport vehicle while an elongate discharge hopper 12 carried by the front of the machine dispenses and spreads the aggregate upon the surface to be paved. A pair of aggregate conveyors 13 and 14 carry a continuous flow of paving material from the bottom of the receiving hopper 11 and deposits the material into the open top of the discharge hopper 12.

The improved paving machine as herein illustrated incorporates a pair of inclined screens or grizzlies 17 and 13 extending downwardly from the discharge ends of the aggregate conveyors 13 and 14 respectively, and spanning the mouth 19 of the discharge hopper 12. A horizontal bar 20, capable of reciprocal motion as indicated by the double headed arrow 21, is supported by the machine frame and extends laterally under the discharge ends of the aggregate conveyors 13 and 14. The rod 20 forms the upper edge of the screens 17 and 18. Angle supports 22, secured to the front edge 23 of the discharge hopper 12,

support the lower ends of the screens. An expulsion conveyor 24 (which will hereafter be described in further detail) extends along the front panel 23 of the inclined screens 17 and 18. The expulsion conveyor empties into a chute 25 aflixed to the end of the discharge hopper 12.

FIG. 2 specifically illustrates the drive means for the expulsion conveyor 24. A drive chain 26 having a protective cover 27 is driven by a sprocket attached to the power shaft of the aggregate spreader located in the bottom of the discharge hopper. While not herein specifically illustrated, the conveyor drive mechanism will be readily apparent to those skilled in the art. An angle drive transmission 28 receives power from the drive chain 26 and in turn rotates the shaft 29. Pillow blocks 30 provide bearing support for the forward end of the shaft 29. Flexible drive couplings 31 provide for any possible misalignment between the angle drive transmission 28 and the pillow blocks 30.

The expulsion conveyor 24 consists of a pair of parallel endless chains 32 and 32a each in driving engagement with sprockets carried by the shaft 29. A series of spaced cross members 33 are welded or otherwise affixed to the chains 32 and 32a. An elongate platform 34, contacting the undersurface of the cross members 33, is secured to the front panel 23 of the discharge hopper 12 and forms the base for the expulsion conveyor 24.

FIG. 3 illustrates various details of the aggregate screen and oversized material expulsion system of the device of FIG. 1. A chain 37 suspended from the angle bracket 22 forms a flexible coupling for the lower end of the screen 17. A connecting link 38 depending from the upper screen mount 20 engages an eccentric 39 and provides reciprocal motion to the upper screen mount 20'. The eccentric 39 is powered by a motor 40, however, as will be apparent to those skilled in the art, a power take-off system similar to that used to drive the chain 26 would form an appropriate substitution. As schematically illustrated in this view, a mixture of paving aggregate 41 and oversized particles 42 are carried by the aggregate conveyor 13 and discharged onto the top of the screen 17. The vibrating screen 17 allows the passage of sized aggregate 41 into the mouth 19 of the discharge hopper 12 while urging the rejected materials 42 onto the expulsion conveyor 24. Inclined guides 43 and 44, extending over the chains 32 and 32a funnel the oversized material 42 onto the plate 34 into the path of the cross members 33 which moves the rejected material to the discharge chute 25.

FIG. 4 further illustrates the operation of the expulsion conveyor 24, which is a common drag chain conveyor. Rejected material leaving the screen 17 is deflected by the guide 43 onto the plate 34, into the path of the cross member 33. A sprocket 47 secured to the drive shaft 29 engages the chain 32. As the chain 32 advances, in the direction of the arrow 48, the attached cross members 33 wipe the upper surface of the plate 34, and pull the rejected material ahead into the chute 25.

to persons skilled in the art having regard for the disclosure hereof. To the extent that such modifications and variations do not depart from the spirit of the invention they are intended to be included within the scope thereof which is not limited to the device specifically illustrated in the drawings but rather only by a just interpertation of the following claims.

Having fully described the invention in such manner as to enable those skilled in the art to understand and practice the same, I claim:

1. In a road paving machine having a receiving hopper to accept paving aggregate, a discharge hopper to dispense and spread the aggregate upon the surface to be paved, and an aggregate conveyor communicating between the receiving hopper and the discharge hopper, the improvements in combination therewith adapted to separate oversized material, including trash, agglomerates, and foreign material, from the aggregate prior to introduction into the discharge hopper and further adapted to expel the rejected material remote from the surface to be paved, said improvements comprising:

(a) an inclined screen extending downwardly from the discharge end of the aggregate conveyor and spanning the mouth of the discharge hopper, said screen intercepting the flow of aggregate from the aggregate conveyor into the discharge hopper and allowing the passage of sized aggregate while suspending oversized material; and

b) an expulsion conveyor extending along the lower edge of the inclined screen, and positioned to receive the oversize material from the screen.

2. The improved paving machine of claim 1, wherein said inclined screen includes drive means for vibrating said screen.

3. The inclined screen of claim 2, including:

(a) a flexible coupling supporting the forward lower end of said screen adjacent said transverse conveyor; and

(b) an eccentric drive means secured to the upper rear end of said screen, said eccentric drive means capable of imparting reciprocal motion to said screen.

References Cited UNITED STATES PATENTS 1,172,012 2/1916 Curtis 9444 2,201,493 5/ 1940 Jorgensen 94-44 X 2,201,534 5/1940 Hallenbeck 94-44 2,783,698 3/1957 Bambi 94-44 X 2,906,438 9/1959 Carpenter 94-44 X NILE C. BYERS, JR., Primary Examiner. 

